Spare tire carrier-lifters have been known for sometime. Early proposals are shown in U.S. Pat. Nos. 2,661,130; 3,734,323; 3,542,413; 3,554,397; 3,865,264; and 3,874,536.
Recently, spare tire carrier-lifting devices have aggregated a number of known elements. Generally this aggregation united a take-up reel for taking up the cable secured to the spare tire for raising and lowering the spare tire relative to the carrier, a speed reducing device for transferring maximum torque from drive means (for example, a manual drive or electric motor) and a torque limiting device to protect the overall structure when excess force is applied. Recent proposals are shown in U.S. Pat. Nos. 4,544,136; 4,535,973 and 4,625,947.
U.S. Pat. No. 4,544,136 purports to disclose in one configuration, apparatus for use in providing a tire lift/carrier comprising a plurality of plates secured together in a side-by-side face abutted relation to form the body of a spool, said spool having a passage for receiving therethrough a shaft on which said spool may be mounted in use, outermost of said plates having identical apertures forming parts of said passage the size of which is complementary to the cross section of the shaft to be applied in said passage, plates adjacent and immediately inward of the outermost of said plates having identical apertures forming parts of said passage the cross section of which is larger than that defined by the apertures in said outermost of said plates and the central of said plates being formed with an inner edge the circumferential extent of which is less than 360 and bounds said passage in part and is interrupted by a substantially radial opening which extends to and through a recessed track defined in said spool at the outer periphery of said central of said plates and thin plate means defining an internal gear having a press fit connection to and forming an extension of one end of said spool. The said patent also discloses torque limiters in FIG. 8 and 11 carrying depressions or recesses in the periphery of a plate to be rotated and cam elements for normally being carried in depressions or radial recesses for the transfer of torque and being forced radially out of the recesses when the torque cannot be transferred.
U.S. Pat. No. 4,535,973 purports to disclose a tire carrier winch for mounting to the underside of a vehicle for raising and lowering a spare tire between storage and access positions comprising, in combination, a housing, a driveshaft rotatably mounted upon said housing, a sheave rotatably mounted within said housing upon said driveshaft, a strand wound upon said sheave, an opening defined in said housing in substantial radial alignment with said sheave, said strand extending through said opening, a drive member connected to said shaft driving connected to said sheave upon rotation of said shaft, a drive member locking member within said housing shiftable between a lock position preventing rotation of said drive member and a drive member release position, and activating means connected to said locking member located adjacent said housing opening and engaging said strand adjacent said opening, said activating means shifting said locking member from said drive member release position to said lock position upon said strand being fully unwound from said sheave. The drive member is a spring finger drive plate carrying a plurality of spring fingers extending from the periphery and drive plate. Each spring finger deforms downwardly out of the plane of the spring finger drive plate for normally sitting in a notch in the drive plate. The reception of the six spring fingers 46 into the six notches 48 produces a frictional driving connection between the plate 40 and drive plate 44, but upon the torque transfer between these components exceeding the frictional interconnection, the spring fingers will ride out of the notches causing relative rotation between the plates producing a torque limiting connection between the driveshaft 22 and the sheave 25.
U.S. Pat. No. 4,625,947 purports to disclose in one configuration, apparatus including a clutch for use in connecting a drive shaft to a device mounted thereon for rotation relative thereto which is used to lift or maintain a load not in excess of a predetermined limit, for example, a tire lift/carrier, comprising a clutch plate connected to the shaft for rotation therewith, a further plate mounted to and for rotation on said shaft in an immediately following relation to said clutch plate, said further plate having the shape of a cup comprising a base portion and generally perpendicular thereto a shallow wall portion, said clutch plate being nested in said cup and having springs engaged thereto in a generally circular arrangement thereof, a plurality of said springs each having a portion thereof projecting outwardly of the outer peripheral boundary of said clutch plate and formed on a uniform radius and to include a further projection centered between its ends which has the shape of a tit, said projecting portions being in a substantially coplannar relation, said shallow wall portion presenting to the interior of said cup at each of a number of locations which are circularly spaced a wall formation arranged to receive and lodge one of said tits, each said tit being normally lodged and laterally contained in one of said wall formations to provide a normally positive and secure drive of said further plate and the device to which it is connected, on rotation of said shaft, absent said device being subjected to a load in excess of said predetermined limited.
It is therefore an object of this invention to provide improved components suitable for use in carrier-lifting devices.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of embodiments thereof.